Will a PWM header work without a tach signal?

[VanGoghComplex]

I've got a PWM fan header on my mobo which I want to use to control a 2-wire watercooling pump. The pump is 6w, so I know the header will have the juice for it.

I found a little chiclet made by Phobya that will turn a PWM signal into a corresponding voltage level, so you can control 3-wire fans from a PWM header.

Thing is, my pump has no tach wire. I don't know if the PWM output will function without some kind of speed feedback.

Anyone else done anything comparable and have some insight?

 

[doyll]

PWM control does not need rpm signal lead, but not sure your motherboard speed control will function properly. Many newer motherboards need their 'fan tuning' function to run and determine fan rpm range before custom rpm curves will give full range control. We would need to know you motherboard model to determine that.

I've no experience with this converter, but other PWM to variable voltage fan converters I've tested gave different voltage ranges depending on fan/pump amp load .. low amp loads gave with a higher minimum voltage to 12v maximum range (9-12v), and higher amp loads give lower minimum voltage but also lower maximum voltage range (5-10.5v). The ranges given are guesstimates ..actual voltage range depends on actual load.

What pump do you have? Many pumps are not really designed to run on variable voltage.

 

[VanGoghComplex]

PWM control does not need rpm signal lead, but not sure your motherboard speed control will function properly. Many newer motherboards need their 'fan tuning' function to run and determine fan rpm range before custom rpm curves will give full range control. We would need to know you motherboard model to determine that.

I've no experience with this converter, but other PWM to variable voltage fan converters I've tested gave different voltage ranges depending on fan/pump amp load .. low amp loads gave with a higher minimum voltage to 12v maximum range (9-12v), and higher amp loads give lower minimum voltage but also lower maximum voltage range (5-10.5v). The ranges given are guesstimates ..actual voltage range depends on actual load.

What pump do you have? Many pumps are not really designed to run on variable voltage.

It's an XSPC Ion pump/reservoir combo. I'm already running it at reduced voltage using one of those little potentiometer boxes. I can't run it full bore; it sucks air no matter how full. If it's being damaged by the lower voltage, I see no sign of it...

It's a 6w pump, so I'm guessing it's on the light end of things as far as load goes.

 

[doyll]

It's an XSPC Ion pump/reservoir combo. I'm already running it at reduced voltage using one of those little potentiometer boxes. I can't run it full bore; it sucks air no matter how full. If it's being damaged by the lower voltage, I see no sign of it...

It's a 6w pump, so I'm guessing it's on the light end of things as far as load goes.

Then probably okay on lower voltage. Obviously needs to be enough to start pump when you turn on computer. Your system has to have air in it or pump wouldn't be sucking it. But if everything is staying cool I guess it's not a problem.

6w is 0.5amp so while not huge amount of power much more than most fans are. Typical fans are like 1-3w with a few up to 6w.

 

[VanGoghComplex]

Then probably okay on lower voltage. Obviously needs to be enough to start pump when you turn on computer. Your system has to have air in it or pump wouldn't be sucking it. But if everything is staying cool I guess it's not a problem.

6w is 0.5amp so while not huge amount of power much more than most fans are. Typical fans are like 1-3w with a few up to 6w.

Yep, there's a little bubble trapped at the top of the res and my return line shoots right at it. So, when it gets turbulent, air goes into the pump... Don't have a whole lot of room to try and remedy it; it's in a Raijintek Metis mini-ITX case.

I'll give one of those little Phobya converters a try. If it doesn't work, I'll use it on my non-PWM Gentle Typhoon I've got in the case. I'll report back either way. Thanks for the insight. Maybe if the mobo's "fan tuning" behavior gets in the way, I can use something like SpeedFan to override it.

 

[doyll]

Yep, there's a little bubble trapped at the top of the res and my return line shoots right at it. So, when it gets turbulent, air goes into the pump... Don't have a whole lot of room to try and remedy it; it's in a Raijintek Metis mini-ITX case.

I'll give one of those little Phobya converters a try. If it doesn't work, I'll use it on my non-PWM Gentle Typhoon I've got in the case. I'll report back either way. Thanks for the insight. Maybe if the mobo's "fan tuning" behavior gets in the way, I can use something like SpeedFan to override it.

Thanks. Look forward to seeing how the Phobya converter works. If possible could you take volage at percent PWM signal and amp/watt load of pump? That way we can graph and see how it performs. Basically a test and review of it

 

[VanGoghComplex]

Thanks. Look forward to seeing how the Phobya converter works. If possible could you take volage at percent PWM signal and amp/watt load of pump? That way we can graph and see how it performs. Basically a test and review of it

I can grab voltage, but I blew the fuse in my cheap multimeter a long time ago... we'll see. Been looking for an excuse to replace it anyway. XD